/*
* @(#)NntpClient.java 1.16 95/08/29 Jonathan Payne, James Gosling
*
* Copyright (c) 1994 Sun Microsystems, Inc. All Rights Reserved.
*
* Permission to use, copy, modify, and distribute this software and its
* documentation for NON-COMMERCIAL purposes and without fee is hereby
* granted provided that this copyright notice appears in all copies. Please
* refer to the file "copyright.html" for further important copyright and
* licensing information.
*
* SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF THE
* SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
* IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,
* OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY
* LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR
* ITS DERIVATIVES.
*/
package sun.net.nntp;
import java.io.*;
import java.util.*;
import java.net.*;
import sun.net.TransferProtocolClient;
import sun.net.TelnetInputStream;
/**
* This class implements network news clients (NNTP).
*
* @version 1.9, 12 Dec 1994
* @author Jonathan Payne, James Gosling
*/
public class NntpClient extends TransferProtocolClient {
public static final int NNTP_PORT = 119;
String serverName; /* for re-opening server connections */
int serverPort;
public NntpClient () {
}
/** Create new NNTP Client connected to host <i>host</i> */
public NntpClient (String host) throws IOException {
super();
openServer(host, NNTP_PORT);
}
/**
* Open a connection to the NNTP server.
* @exception NntpProtocolException did not get the correct welcome message
*/
public void openServer(String name, int port) throws IOException {
serverName = name;
serverPort = port;
super.openServer(name, port);
if (readServerResponse() >= 300)
throw new NntpProtocolException("Welcome message");
}
/** Sends command <i>cmd</i> to the server. */
public int askServer(String cmd) throws IOException {
int code = 503;
for (int tries = 3; --tries >= 0;) {
try {
serverOutput.print(cmd);
code = readServerResponse();
if (code < 500)
return code;
/*
* errors codes >500 usually result from something happening
* on the net. Its usually profitable to disconnect and
* reconnect
*/
} catch(Exception e) {
}
/* reconnect to the server */
try {
serverOutput.close();
} catch(Exception e2) {
}
openServer(serverName, serverPort);
}
return code;
}
InputStream makeStreamRequest(String cmd, int reply) throws IOException {
int response;
response = askServer(cmd + "\r\n");
if (response != reply) {
String msg = null;
try {
for (int i = 0; i < 99; i++) {
String n = (String) serverResponse.elementAt(i);
if (msg == null)
msg = n;
else
msg = msg + "\n" + n;
}
} catch(Exception e) {
};
if (msg == null)
msg = "Command " + cmd + " yielded " + response + "; expecting " + reply;
throw new NntpProtocolException(msg);
}
switch (response / 100) {
case 1:
case 2:
break;
case 3:
throw new NntpProtocolException("More input to command expected");
case 4:
throw new NntpProtocolException("Server error - cmd OK");
case 5:
throw new NntpProtocolException("Error in command: " + cmd);
}
return new NntpInputStream(new TelnetInputStream(serverInput, false));
}
String tokenize(String input)[] {
Vector v = new Vector();
StringTokenizer t = new StringTokenizer(input);
String cmd[];
while (t.hasMoreTokens())
v.addElement(t.nextToken());
cmd = new String[v.size()];
for (int i = 0; i < cmd.length; i++)
cmd[i] = (String) v.elementAt(i);
return cmd;
}
/**
* Get information about group <i>name</i>.
* @exception UnknownNewsgroupException the group name wasn't active.
* @exception NntpProtocolException received an unexpected reply.
*/
public NewsgroupInfo getGroup(String name) throws IOException {
switch (askServer("group " + name + "\r\n")) {
case 411:
throw new UnknownNewsgroupException(name);
default:
throw new NntpProtocolException("unexpected reply: "
+ getResponseString());
case 211:
{
String tokens[] = tokenize(getResponseString());
int start;
int end;
start = Integer.parseInt(tokens[2]);
end = Integer.parseInt(tokens[3]);
return new NewsgroupInfo(name, start, end);
}
}
}
/** Set the current group to <i>name</i> */
public void setGroup(String name) throws IOException {
if (askServer("group " + name + "\r\n") != 211)
throw new UnknownNewsgroupException(name);
}
/** get article <i>n</i> from the current group. */
public InputStream getArticle(int n) throws IOException {
return makeStreamRequest("article " + n, 220);
}
/** get article <i>id</i> from the current group. */
public InputStream getArticle(String id) throws IOException {
if (id.charAt(0) != '<')
id = "<" + id + ">";
return makeStreamRequest("article " + id, 220);
}
/** get header of article <i>n</i> from the current group. */
public InputStream getHeader(int n) throws IOException {
return makeStreamRequest("head " + n, 221);
}
/** get header of article <i>id</i> from the current group. */
public InputStream getHeader(String id) throws IOException {
if (id.charAt(0) != '<')
id = "<" + id + ">";
return makeStreamRequest("head " + id, 221);
}
/** Setup to post a message. It returns a stream
to which the article should be written. Returns null if the post
is disallowed. The article must have a properly formed RFC850 header
and end-of-lines must by sent as \r\n. The Article must end with
\r\n */
public PrintStream startPost() throws IOException {
return askServer("post\r\n") == 340 ? serverOutput : null;
}
/** Finish posting a message. Must be called after calling startPost
and writing the article. Returns true if the article is posted
successfully. */
public boolean finishPost() throws IOException {
return askServer(".\r\n") == 240;
}
}